Hybrid drive system and shifting method

Abstract

The invention relates to a hybrid drive system, comprising: an internal combustion engine (12) having a crankshaft (14); an electric machine (16) having a rotor (18) and a stator (20); a dual clutch transmission (30), which has an input shaft (E0), a dual claw clutch (31) with a first claw clutch (K1) and a second claw clutch (K2), a first sub-transmission (TG1) and a second sub-transmission (TG2), wherein the first claw clutch (K1) is provided for rotationally coupling a first sub-transmission input shaft (E1) of the first sub-transmission (TG1) to the input shaft (E0), wherein the second claw clutch (K2) is provided for rotationally coupling a second sub-transmission input shaft (E2) of the second sub-transmission (TG2) to the input shaft (E0), wherein the rotor (18) is arranged so as to be able to transfer torque from the rotor (18) to the dual clutch transmission via the second sub-transmission input shaft (E2) at the output side of the second claw clutch (K2) into the dual clutch transmission.

Description

[0001] The invention relates to a hybrid drive system and a gear shifting method for the hybrid drive system.

[0002] DE 10 2006 036 758 A1 has disclosed a hybrid drive system with a dual clutch transmission having a double claw clutch. Two electric machines are provided in the hybrid drive system, wherein a respective electric machine is assigned to each of the two sub-transmissions of the dual clutch transmission. With the aid of the two electric machines and their arrangement, the power shifting capability of the hybrid drive system is ensured during each gear shift.

[0003] The object of the present invention is to improve the above-mentioned hybrid drive system in order to reduce the production costs and the required installation space overall, while the function of the hybrid drive system should be as little affected as possible. This object is achieved by a hybrid drive system according to claim 1 and a hybrid drive system shifting method according to claims 2 to 4.

[0004] The present invention is based on a hybrid drive system, which includes: an internal combustion engine with a crankshaft; an electric motor with a rotor and a stator; a dual-clutch transmission, which has an input shaft, a dual-claw clutch with a first claw clutch and a second claw clutch, a first sub-transmission and a second sub-transmission, wherein the first sub-transmission advantageously has a first shifting clutch and a third shifting clutch, wherein the second sub-transmission advantageously has a second shifting clutch, wherein the first claw clutch is also configured to connect the first sub-transmission input shaft of the first sub-transmission to the input shaft in a rotationally fixed manner, wherein the second claw clutch is configured to connect the second sub-transmission input shaft of the second sub-transmission to the input shaft in a rotationally fixed manner.

[0005] In this case, the rotor is arranged in such a way that the torque can be introduced from the rotor on the secondary side of the second claw clutch via the second sub-transmission into the dual-clutch transmission.

[0006] The rotor is particularly advantageously engaged or engageable with the second sub-transmission input shaft in such a way that a torque can be introduced from the rotor on the secondary side of the second claw clutch via the second sub-transmission input shaft into the dual clutch transmission.

[0007] In this case, the internal combustion engine, the dual clutch transmission and the differential are advantageously arranged one after the other in the stated sequence in the direction of torque flow.

[0008] A sub-transmission is a part of a dual-clutch transmission, which includes a spur gear pair assigned to one of the two sub-transmission input shafts of the dual-clutch transmission. The spur gear pair of the sub-transmission includes gears that are arranged coaxially with the corresponding sub-transmission input shaft and are rotationally fixedly engaged or can be engaged with the corresponding sub-transmission input shaft, and gears that mesh with these gears and are arranged coaxially with one or more intermediate shafts of the dual-clutch transmission.

[0009] A claw clutch is a form-fitting clutch. A shifting clutch is a clutch of a sub-transmission which is associated with a switchable spur gear pair of the sub-transmission. Each switchable spur gear pair has a fixed gear and an engageable movable gear. Advantageously, the fixed gear is arranged coaxially with the input shaft of the sub-transmission and is connected thereto in a rotationally fixed manner. Advantageously, each switchable spur gear pair has a movable gear which is arranged coaxially with the intermediate shaft and can be connected thereto in a rotationally fixed manner by means of a shifting clutch. The opposite is also possible, i.e. the switchable movable gear is arranged on the input shaft of the sub-transmission and the fixed gear meshing therewith is arranged on the intermediate shaft.

[0010] A “rotationally fixed coupling of two rotatably mounted elements” means that the two elements are arranged coaxially to one another and are connected to one another by rotating at the same angular speed.

[0011] The input shaft of a dual-clutch transmission is a shaft which is arranged between the internal combustion engine and the double dog clutch with respect to the torque flow from the internal combustion engine. This means that the torque to be transferred from the internal combustion engine to the dual-clutch transmission is transmitted completely via the input shaft and further via the double dog clutch to the sub-transmission.

[0012] The sub-transmission input shaft is arranged downstream of the double dog clutch in terms of torque flow. The first sub-transmission input is coupled to the output side of the first dog clutch in a rotationally fixed manner. The second sub-transmission input shaft is coupled to the output side of the second dog clutch in a rotationally fixed manner.

[0013] In terms of torque flow, the electric machine rotor is engaged to the second sub-transmission downstream of the dual clutch.

[0014] The rotor is directly coupled to the second input shaft or can be coupled to the second input shaft via a further rotor clutch.

[0015] The term "coupling of two rotatably mounted elements" means that the two elements are arranged coaxially or axis-parallel to each other and they are coupled to each other by rotating at a constant speed ratio.

[0016] The secondary side of the clutch refers to the side of the clutch that is located downstream in terms of the torque flow. Therefore, the secondary side of the clutch begins with the clutch half of the clutch that is located downstream.

[0017] According to the invention, on the one hand, exactly one electric machine is provided, namely the electric machine described above. On the other hand, according to the invention, a separating clutch is provided in the form of a friction clutch, which is designed to couple the crankshaft to the input shaft in a rotationally fixed manner.

[0018] However, compared with the prior art, the axial length of the hybrid drive system is increased by the additional separation clutch. In addition, the control and regulation costs in certain gear changes are increased. However, compared with the prior art, the manufacturing costs can be reduced overall by reducing the motor.

[0019] It has been shown that load-free shifting with sufficiently high quality is possible using the hybrid drive system according to the invention, provided that the electric machine is coupled to one of the two sub-transmissions on the secondary side of the dual clutch and provided that the separating clutch is designed as a friction clutch.

[0020] A friction clutch is a clutch with friction disks or preferably a multi-plate clutch. Friction-locking separating clutches are advantageously used for load-free shifting of hybrid drive systems.

[0021] When shifting from an initial gear in internal combustion engine driving, at least the following two steps are advantageously performed in the stated order:

[0022] - increase the torque of the electric machine and disengage the friction clutch, engage the next shifting clutch and disengage the current shifting clutch,

[0023] - The friction-locking separating clutch is engaged, increasing the torque of the internal combustion engine and reducing the torque of the electric machine.

[0024] Internal combustion engine drive refers to the generation of an output torque output by the dual clutch transmission, wherein the internal combustion engine provides all the required torque, or the internal combustion engine and the electric machine provide the required torque. Internal combustion engine drive therefore refers to a drive in which the internal combustion engine provides at least part of the torque.

[0025] Advantageously, a distinction is made here between a method for shifting from an engaged gear in a first subtransmission to an engaged gear in a second subtransmission coupled to the electric machine and a method for shifting from an engaged gear in the second subtransmission to an engaged gear in the first subtransmission.

[0026] Particularly advantageously, in order to shift from internal combustion engine drive via the first sub-transmission (where the separating clutch, the first dog clutch and the first shifting clutch of the first sub-transmission are all engaged) to internal combustion engine drive via the second sub-transmission (where the separating clutch, the second dog clutch and the second shifting clutch of the second sub-transmission are all engaged), the following steps are performed in the stated order:

[0027] - engaging the second shift clutch,

[0028] - Disengage the clutch,

[0029] - opening the first dog clutch and / or opening the first shift clutch,

[0030] - engage the second dog clutch,

[0031] - Engage the disconnect clutch (K0).

[0032] Further advantageous embodiments of the invention emerge from the dependent claims and the following description of the drawings.

[0033] The only Figure 1 A hybrid drive system 10 for a motor vehicle is shown schematically.

[0034] The hybrid drive system 10 has an internal combustion engine 12 and an electric motor 16, both of which are used together or separately as a drive machine for a motor vehicle. The hybrid drive system 10 also has a dual clutch transmission 30 and an axle transmission / differential 32. The internal combustion engine 12, the dual clutch transmission 30 and the differential 32 are arranged in succession in the order described with respect to the torque flow from the internal combustion engine 12 to the differential 32. Similarly, the electric motor 16, the dual clutch transmission 30 and the differential 32 are arranged in succession in the order described with respect to the torque flow from the electric motor 16 to the differential 32.

[0035] The electric machine 16 has a stator 20 connected to a housing (not shown) and a rotor 18 rotatably mounted relative to the stator. The internal combustion engine 12 has a crankshaft 14 .

[0036] The dual clutch transmission has an input shaft E0 which can be coupled to the crankshaft in a rotationally fixed manner by means of a separating clutch K0 . The input shaft E0 is therefore coupled in a rotationally fixed manner to the clutch half or output side of the separating clutch K0 which is arranged downstream with respect to the torque flow from the internal combustion engine 12 .

[0037] The double dog clutch 31 of the double clutch transmission 30 is arranged downstream of the disconnect clutch K0 and downstream of the input shaft E0 with respect to the torque flow from the internal combustion engine 12. The double dog clutch 31 has a first dog clutch K1, whose input side or first clutch half is coupled to the input shaft E0 in a rotationally fixed manner. The double clutch 31 has a second dog clutch K2, whose input side or first clutch half is also coupled to the input shaft E0 in a rotationally fixed manner.

[0038] The dual clutch transmission 30 has a first sub-transmission TG1 and a second sub-transmission TG2 .

[0039] The output side or second clutch half of the first claw clutch K1 is coupled in a rotationally fixed manner to the first sub-transmission input shaft E1 of the first sub-transmission TG1. The output side or second clutch half of the second claw clutch K2 is coupled in a rotationally fixed manner to the second sub-transmission input shaft E2 of the second sub-transmission TG2.

[0040] In other words, the first claw clutch K1 is designed to couple the input shaft E0 and the first sub-transmission input shaft E1 to each other in a rotationally fixed manner in the engaged state. The second claw clutch K2 is designed to couple the input shaft E0 and the second sub-transmission input shaft E2 to each other in a rotationally fixed manner in the engaged state.

[0041] According to the invention, the separating clutch K0 is designed as a friction clutch and according to the invention, the electric machine 16 is the only electric machine of the hybrid drive system.

[0042] It is important for the present invention that the rotor 18 of the electric machine 16 is engaged in a torque-transmitting manner to one of the two sub-transmissions TG1, TG2 downstream of the dual clutch 31 with respect to the torque flow from the internal combustion engine 12. In other words, the rotor 18 is engaged to the dual clutch transmission 30 in such a way that, with respect to the torque flow from the internal combustion engine 12, the torque is introduced into the dual clutch transmission 30 starting from the rotor 18 only downstream of the dual clutch 31.

[0043] In the specific embodiment of the figure, the first engagement gear A1 is connected to the rotor 18 in a rotationally fixed manner. In addition, the second engagement gear A2 is connected to the second sub-transmission input shaft E2 in a rotationally fixed manner. The first engagement gear A1 and the second engagement gear A2 are arranged so that they are permanently meshed with each other. The first engagement gear A1 and the second engagement gear A2 are engaged with each other in a torque-transmitting manner.

[0044] Alternatively, a belt drive or one or more spur gear stages / pairs of spur gears may be arranged between the first engagement gear A1 and the second engagement gear A2. In addition, with respect to the torque flow between the first engagement gear A1 and the second engagement gear A2, another clutch for interrupting and connecting the torque flow may be provided. It is also possible to omit the second engagement gear A2 and instead engage the first engagement gear A1 in a torque-transmitting manner to one of the gears G2, G4 of the second sub-transmission TG2. In other words, the rotor 18 may be engaged to the second sub-transmission TG2 in such a way that, starting from the rotor 18, torque may be transferred into the dual clutch transmission via the second gear G2 or the fourth gear G4.

[0045] The first sub-transmission TG1 comprises a first sub-transmission input shaft E1 , a first sun gear Z1 arranged coaxially with the first sub-transmission input shaft E1 , a first gear G1 arranged coaxially with the first countershaft VW1 , and a third gear G3 arranged coaxially with the second countershaft VW2 .

[0046] The first sun gear Z1 and the first gear wheel G1 form a first shiftable spur gear pair, which is assigned to the first shifting clutch S1. The first shifting clutch S1 is designed to connect the first sub-transmission input shaft E1 to the first countershaft VW1 in a torque-transmitting manner via the first shiftable spur gear pair.

[0047] The first sun gear Z1 and the third gear gear G3 form a third shiftable spur gear pair, which is assigned to a third shifting clutch S3. The third shifting clutch S3 is designed to connect the first sub-transmission input shaft E1 to the second countershaft VW2 in a torque-transmitting manner.

[0048] In the embodiment of the figure, the first sun gear Z1 is designed as a fixed gear, which is connected to the first sub-transmission input shaft E1 in a rotationally fixed manner. The first gear G1 is designed as a movable gear arranged coaxially with the first intermediate shaft VW1, and the third gear G3 is designed as a movable gear arranged coaxially with the second intermediate shaft VW2. The first shifting clutch S1 is therefore arranged coaxially with the first intermediate shaft VW1 and is designed to connect the first gear G1 to the first intermediate shaft VW1 in a rotationally fixed manner. The third shifting clutch S3 is arranged coaxially with the second intermediate shaft VW2 and is designed to connect the third gear G3 to the second intermediate shaft VW2 in a rotationally fixed manner.

[0049] The second sub-transmission TG2 comprises a second sub-transmission input shaft E2, a second sun gear Z2 arranged coaxially with the second sub-transmission input shaft E2, a fourth gear G4 arranged coaxially with the first countershaft VW1 and a second gear G2 arranged coaxially with the second countershaft VW2.

[0050] The second sun gear Z2 and the fourth gear gear G1 form a fourth shiftable spur gear pair, which is assigned to a fourth shifting clutch S4. The fourth shifting clutch S4 is designed to connect the second sub-transmission input shaft E2 to the first countershaft VW1 in a torque-transmitting manner via the fourth shiftable spur gear pair.

[0051] The second sun gear Z2 and the second gear G2 form a second shiftable spur gear pair, which is assigned to the second shifting clutch S2. The second shifting clutch S2 is designed to connect the second sub-transmission input shaft E2 to the second countershaft VW2 in a torque-transmitting manner via the second shiftable spur gear pair.

[0052] In the embodiment of the figure, the second sun gear Z2 is designed as a fixed gear, which is connected to the second sub-transmission input shaft E2 in a rotationally fixed manner. The fourth gear gear G4 is designed as a movable gear arranged coaxially with the first intermediate shaft VW1, and the second gear gear G2 is designed as a movable gear arranged coaxially with the second intermediate shaft VW2. Therefore, the fourth shifting clutch S4 is arranged coaxially with the first intermediate shaft VW1 and is designed to connect the fourth gear gear G4 to the first intermediate shaft VW1 in a rotationally fixed manner. The second shifting clutch S2 is arranged coaxially with the second intermediate shaft VW2 and is designed to connect the second gear gear G2 to the second intermediate shaft VW2 in a rotationally fixed manner.

[0053] To remove torque from the dual clutch transmission 30 , a first output gear F1 is arranged on the first countershaft and a second output gear F2 is arranged on the second countershaft. The first output gear F1 is rotationally fixedly coupled to the first countershaft VW1 and the second output gear F2 is rotationally fixedly coupled to the second countershaft VW2.

[0054] Both the first output gear F1 and the second output gear F2 mesh with the differential input gear D of the differential 32. Therefore, starting from the output gears F1, F2, the torque from the dual clutch transmission is introduced into the differential 32.

[0055] The rotor rotation axis 22 of the rotor 18 , the crankshaft rotation axis 24 of the crankshaft 14 and the half-shaft rotation axis 34 of the differential 32 are all arranged in an axially parallel manner and axially offset to one another.

[0056] In order to shift from internal combustion engine drive via the first sub-transmission TG1 (where the separating clutch K0, the first claw clutch K1 and the first shifting clutch S1 of the first sub-transmission are all engaged and the second claw clutch is preferably disengaged) to internal combustion engine drive via the second sub-transmission TG2 (where the separating clutch K0, the second claw clutch K2 and the second shifting clutch S2 of the second sub-transmission TG2 are engaged and the first claw clutch is preferably disengaged), the following steps, each separated by a dash, are particularly preferably performed in the order described:

[0057] - engaging the second shifting clutch S2 or, in general with regard to the invention: engaging the target gear in the second sub-transmission TG2 and preferably reducing the torque of the internal combustion engine 12 and increasing the torque of the electric machine 16 ,

[0058] - the separator clutch K0 is opened, so that after this step, purely electric drive via the dual clutch transmission 30 now takes place temporarily,

[0059] - opening the first claw clutch K1 and / or opening the first shifting clutch S1,

[0060] - engaging the second claw clutch K2 , wherein at the latest at the end of this step both the first claw clutch K1 and the first shifting clutch S1 should be disengaged,

[0061] - Engaging the separating clutch ( K0 ), increasing the torque of the internal combustion engine 12 and reducing the torque of the electric machine 16 .

[0062] The term "internal combustion engine driven" refers to a driving form in which the internal combustion engine 12 is at least partially involved. Therefore, it refers not only to a driving form in which the internal combustion engine 12 is the only driving source, but also to a driving form in which the internal combustion engine 12 and the motor 16 are shared driving sources.

[0063] In order to shift from internal combustion engine drive via the second sub-transmission TG2 (where the separating clutch K0, the second dog clutch K2 and the second shifting clutch S2 of the second sub-transmission TG2 are engaged) to internal combustion engine drive via the first sub-transmission TG1 (where the separating clutch K0, the first dog clutch K1 and the third shifting clutch S3 of the first sub-transmission TG1 are engaged), the following steps separated by dashes are performed in the order described:

[0064] - increasing the torque provided by the electric machine 16 and reducing the torque provided by the internal combustion engine 12 and opening the separating clutch K0 and the second dog clutch K2 so that at the end of this method step the electric machine 16 temporarily serves as the sole drive source,

[0065] - engaging the input shaft E0 to the first output gear F1 , preferably by engaging the first dog clutch K1 and engaging the third shifting clutch S3 , wherein one of these two clutches, the first dog clutch K1 or the third shifting clutch S3 , may also have been engaged in the previous step,

[0066] - Engaging the separating clutch K0 and reducing the torque provided by the electric machine 16 and increasing the torque provided by the internal combustion engine.

[0067] Reference numerals list

[0068] 10 Hybrid Drive System

[0069] 12 Internal combustion engine

[0070] 14 Crankshaft

[0071] 16 Motor

[0072] 18 Rotor

[0073] 20 Stator

[0074] 22 Rotor axis of rotation

[0075] 24 Crankshaft rotation axis

[0076] 30 Dual Clutch Transmission

[0077] 31 Double dog clutch

[0078] 32 Differential

[0079] 34 Axle shaft rotation axis

[0080] A1 First engagement gear

[0081] A2 Second engagement gear

[0082] D Differential input gear

[0083] E0 Input shaft

[0084] E1 First sub-transmission input shaft

[0085] E2 Second sub-transmission input shaft

[0086] G1 1st gear

[0087] G2 2nd gear

[0088] G3 Third gear

[0089] G4 Fourth gear

[0090] F1 1st output gear

[0091] F2 Second output gear

[0092] K0 Disengagement clutch

[0093] K1 First Dog Clutch

[0094] K2 Second Dog Clutch

[0095] S1 First shift clutch

[0096] S2 Second shift clutch

[0097] S3 Third shift clutch

[0098] S4 4th gear clutch

[0099] TG1 first sub-transmission

[0100] TG2 Second sub-transmission

[0101] VW1 first intermediate shaft

[0102] VW2 Second intermediate shaft

[0103] Z1 First sun gear

[0104] Z2 Second sun gear

Claims

1. A method for shifting a hybrid drive system, the hybrid drive system comprising: - an internal combustion engine (12) having a crankshaft (14); - an electric machine (16) having a rotor (18) and a stator (20); a dual clutch transmission (30) having an input shaft (E0), a double claw clutch (31) having a first claw clutch (K1) and a second claw clutch (K2), a first sub-transmission (TG1) and a second sub-transmission (TG2), The first sub-transmission (TG1) has a first shifting clutch (S1) and a third shifting clutch (S3), the second sub-transmission (TG2) has a second shifting clutch (S2), The first claw clutch (K1) is provided for coupling the first sub-transmission input shaft (E1) of the first sub-transmission (TG1) to the input shaft (E0) in a rotationally fixed manner, The rotor (18) is arranged to be able to transfer torque from the rotor (18) to the dual clutch transmission (30) via the second sub-transmission (TG2) on the secondary side of the second claw clutch (K2), There is exactly one electric machine, namely the electric machine (16), and a separating clutch (K0) in the form of a friction clutch is designed to connect the crankshaft (14) to the input shaft (E0) in a rotationally fixed manner. The second claw clutch (K2) is provided for coupling the second sub-transmission input shaft (E2) of the second sub-transmission (TG2) to the input shaft (E0) in a rotationally fixed manner. Its characteristics are: In order to shift from the internal combustion engine drive of the second sub-transmission which is engaged via the disconnect clutch, the second dog clutch and the second shifting clutch of the second sub-transmission to the internal combustion engine drive of the first sub-transmission which is engaged via the disconnect clutch, the first dog clutch and the third shifting clutch of the first sub-transmission, the following steps are performed in the following order: - increasing the torque provided by the electric machine and reducing the torque provided by the internal combustion engine and opening the disconnect clutch and the second dog clutch, so that at the end of this step the electric machine temporarily becomes the sole drive source, - one of the first dog clutch and the third shift clutch is engaged in the previous step, and the other of the first dog clutch and the third shift clutch is engaged in this step, thereby engaging the input shaft to the first output gear; or the first dog clutch and the third shift clutch are engaged at the same time in this step, thereby engaging the input shaft to the first output gear, - Engaging the disconnect clutch and reducing the torque provided by the electric machine and increasing the torque provided by the internal combustion engine.

2. The method according to claim 1, characterized in that: In order to shift from an internal combustion engine drive of a first sub-transmission which is engaged via a disconnect clutch, a first dog clutch and a first shifting clutch of a first sub-transmission to an internal combustion engine drive of a second sub-transmission which is engaged via a disconnect clutch, a second dog clutch and a second shifting clutch of a second sub-transmission, the following steps are performed in the following order: - engaging the second shift clutch, reducing the torque of the internal combustion engine and increasing the torque of the electric machine, - opening the separator clutch, so that after this step is completed, purely electric driving via the dual clutch transmission now takes place temporarily, - opening the first dog clutch or opening the first shift clutch, - engaging the second dog clutch, wherein at the latest at the end of this step both the first dog clutch and the first shifting clutch are disengaged, - Engaging the split clutch, increasing the torque of the internal combustion engine and reducing the torque of the electric machine.

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